Convoluted boots made of thermoplastic materials and elastomers are known to exist in many different forms and have been found to be successful as a means for sealing universal joints in motor vehicle applications. Whereas so-called fixed joints with a fixed joint center can only carry out angular movements between two parts, which angular movements have to be accommodated by the sealing convoluted boots under rotating conditions of articulation, the convoluted boots of plunging joints are subject to rotating articulated movements and, simultaneously, plunging movements of the joints. With the increasing plunging distances and greater operating angles of modern joints, the loads to which the respective convoluted boots are subjected also increase.
DE 102 42 428 A1 discloses a convoluted boot for constant velocity universal joints with long plunging distances, which convoluted boot comprises a first boot potion with annular folds of decreasing sizes which are intended to deform largely during angular movements between the first and the second one of the parts. A second boot portion is also included having annular folds of identical sizes which are intended to deform largely during axial plunging movements of the first and the second one of the parts relative to one another. Because the convoluted boot includes two portions each intended to serve a different purpose, it results in a relatively long axial length which may not be desirable in all vehicle applications. For example, such a boot requires a larger installation space which is not always available. The relatively long axial length has a correspondingly large surface area and thus to a large area subject to potential damage which, may lead to reduced boot or joint life. The long plunging distance is combined with a relatively great change in volume which can lead to the annular folds suffering from dents or bulges, which is also disadvantageous.
Accordingly, there exists a need for an improved convoluted boot for sealing an articulating and plunging joint assembly.